The explosive growth of the Internet as a publication and interactive communication platform has created an electronic environment that is changing the way business is transacted. As the Internet becomes increasingly accessible around the world, users need efficient tools to navigate the Internet and to find content available on various websites.
Web advertising supports a large swath of today's Internet ecosystem. A large portion of the advertising market over the Internet consists of textual advertisements or ads, which encompass short text messages distributed to the users. One main advertising channel used to distribute textual ads is the sponsored search advertising channel, which consists in placing ads on the results pages from a web search engine, with ads driven by the originating query. Another main advertising channel is the contextual advertising channel, which refers to the placement of commercial ads within the content of a generic web page.
Given a specific page, rather than placing generic ads, it would be preferable to display ads related to the content of the page to provide a better user experience and to increase the probability of user clicks. Previous approaches estimated the ad relevance based on the co-occurrence of the same words or phrases within the ad and within the page. However, targeting mechanisms based solely on phrases found within the text of the page can lead to erroneous results. For example, a page about a famous golfer named “John Maytag” might trigger an ad for “Maytag dishwashers,” since Maytag is a popular appliance brand. Thus, it would be advantageous to provide a matching mechanism that combines a semantic phase with the traditional keyword matching, also known as syntactic, phase in order to improve the relevance of the displayed ads.